Photographic printing machine



Jan. 22, 1935. HAM 1,988,593

PHOTOGRAPHIC PRINTING MACHINE Filed July 12, 1953 ATTORNEY Patented Jan.22, 1935 UNITED STATES PAT-llN lf OFFICE PHOTOGRAPHIC PRINTING MACHINEGarnet P. Ham, Elizabeth, N. 1., assignor' to Western Electric Company,Incorporated, New; York, N. Y., a corporation of New York- I pApplication July 12, 1933, Serial No. 680,011 v 6 Claims.

This invention relates to a system of optical elements and moreparticularly to a system for reflecting and uniformly distributing lightfrom a source on a predetermined curved area.

An object of the invention is to provide a series of optical elements sorelated as to produce a uniform distribution of light on a movingpredetermined curved surface.

In accordance with a preferred embodiment of the invention herein shownand described, a sheet of blueprint paper and associated negatives arecontinuously moving at a uniform rate of speed over the outer or convexsurface of a curved glass, the surfaces of which are straight inhorizontal planes and curved in vertical planes. Several arc lamps arelocated on the inner or concave surface side of the curved glass toprovide the illumination necessary for printing on the blueprint paper.Individual upright reflectors are located in back of the arc lamps andhave their reflecting surfaces striated in vertical planes to distributethe light from the lamps evenly over the surface of the curved glass. Aconcave reflecting hood having the same contour as the curved glass andstriated in vertical planes faces the concave surface of the glass toreflect that portion of the light from the arc lamps which does not passthrough the curved glass to the paper. This light is reflected back ontothe 30 curved glass uniformly over the surface of the glass.

The invention may be better understood by reference to the followingdetailed description and accompanying drawing in which Fig. 1 is aperspective view of that portion of the blueprinting machine embodyingthe invention;

Fig. 2 is a schematic view of the embodiment of the invention shown inFig. 1, and

Figs. 3 and 4 are views of one of the reflectors employed.

Referring to the drawing which illustrates a preferred embodiment of theinvention, blueprint paper 11 and associated negatives (not shown) asthey are propelled through the machine by means (not shown) pass overthe outer or convex surface of the curved glass 12 which is sometimescalled a hump glass. The paper 11 and the associated negatives are heldin contact with the curved glass 12 throughout its entire height by anysuitable means such as the rollers 13. Several arc lamps 14 are arrangedin a row on the concave side of the curved glass 12.

5 back of each of the arc lamps 14 to throw the Individual reflectors 15are positioned in the light onto the curved glass 12. Each of thereflectors 15 has a central curved portion 16 and straight end portions17. Each reflector 15 is positioned so that the concave surface of thecurved portion 16 is adjacent the arc lamps 14. The reflectors 15 arepreferably made of a metal such as aluminum; and the surface of which,facing the glass 12,*is striated, the striae running in vertical planes.A satisfactory method of producing the striae consists of scratching thereflec tors longitudinally and thereafter etching the scratched surfaceswith an acid such as hydrofluoric acid. This method produces a pluralityof mirrored surfaces comprising vertically extending grooves and ridgeswhich will uniformly distribute the light from the individual arc lampsto the right and left of the lamps and will not concentrate the light onthe glass directly in front of the lamps 14 as might otherwise be thecase.

In back of the individual reflectors 15 is a reflecting hood 18. Thehood 18 is shown in Fig. 1 in its raised position and in Fig. 2 in itslowered or normal position. The hood 18 preferably has the same contouras that of the curved or hump glass 12 and is positioned so that theconcave surface faces the concave surface of the glass 12. The inner orconcave surface of the hood 18 is preferably a metal such as aluminumand the surface is striated, the striae 20 thereon running in verticalplanes. The striae 20 are preferably produced in the manner describedabove with reference to the individual reflectors 15.

In some continuous blueprinting machines used in the past there is amaximum speed at which the paper can be propelled therethrough, beyondwhich speed satisfactory results cannot be obtained. It has been foundwith a system such as shown and described a considerable increase in thespeed of blueprint paper can be made and at the same time equal if notsuperior results can be obtained as compared with machines havingunstriated reflectors and unstriated hoods of cylindrical shape when theglass 12 is not cylindrical in shape.

While the single embodiment of the invention has been shown anddescribed in detail, the invention is not to be construed as limited tothe particular embodiment shown, since numerous modifications thereofcan be made by one skilled in the art without departing from the spiritof applicants invention, the scope of which is determined in theappended claims.

What is claimed is: 1. In a blueprinting machine, a hump glass having aconcave surface and a convex surface, means for propelling a blueprinting paper and associated negatives over the convex surface, areflector having a concave surface facing the concave surface of saidglass, a source of light between said glass and said reflector, theconcave surface of said reflector having a plurality of straightparallel striae thereon.

2. In a blueprinting machine, a hump glass having a convex surface and aconcave surface, means for moving a blueprinting paper in one directionover the convex surface of said hump glass, a reflector having the samecontour as the concave surface of the hump glass with its concavesurface facing the concave surface of the hump glass, and a plurality ofstriae on'said reflector for distributing light reaching the reflectorevenly over said hump glass in a direction perpendicular to thedirection of travel of said paper.

' 3. In a reproducing device, a curved glass having a convex surfaceand- 'a concave surface, means for moving a printing paper andassociated negatives over the convex surface of said glass, apluralityof light sources arranged in a row on the concavesurface side of saidglass, individual striated reflectors in back of each of said lightsources and a reflector hood having the same contour as the concavesurface. of the glass in back of the individual reflectors;

4. In a blueprinting machine, a light transmitter, means for propellingan object across the face of said light transmitter on one side of saidlight transmitter, a reflector facing the other side of said lighttransmitter and having a plurality of striae thereon for distributinglight reaching the reflector evenly over the face on said other side ofthe light transmitter in a direction perpendicular to that in which theobject is propelled.

5. In a blueprinting machine, alight transmitter, means for propellingan object across the face of said light transmitter on one side of thelight transmitter, a reflector facing the other side of said lighttransmitter and having the same contour as the face of the lighttransmitter which the reflector faces,

6. In a blueprinting machine, a light transmitter, means for propellingan object across the face of said light transmitter on one side ofthelight transmitter, a reflector facing the other side of said lighttransmitter and having the samecontour as the face of the lighttransmitter which the reflector faces, and a plurality of striae thereonfor distributing light reaching the reflector evenly over saidother facein a direction perpendicular to that in which the object is propelled.

GARNET P. HAM.

